1. Field of the Invention
The present invention relates to an endless belt for fixing, a fixing device, and a method for producing the endless belt for fixing. These endless belt for fixing and fixing device can be used in copying machines, printers, facsimiles, and image forming apparatuses, such as multifunction peripherals including a plurality of these functions.
2. Description of the Related Art
Conventionally, fixing processing is carried out by heating and pressing a toner image formed on a recording material using a fixing device in an image forming apparatus.
It is proposed to use a fixing belt (an endless belt) using nickel as a base material in such a fixing device.
Specifically, the fixing belts discussed in Japanese Patent Application Laid-Open No. 2010-54666 and No. 2007-286616 are the fixing belts using nickel as the base material, which is produced by an electrocasting method. The electrocasting method is a method for producing a metal film, in which a metal layer is electrically precipitated and grown like a plating step in an electrolytic solution onto a cylindrical surface of carbon or the like and subsequently a shaping with a mold is carried out.
In Japanese Patent Application Laid-Open No. 2010-54666 and No. 2007-286616, phosphorus is added to an entire surface in a thickness direction of the base material (nickel) of the fixing belt for the purpose of enhancing durability of the base material.
For example, in Japanese Patent Application Laid-Open No. 2010-54666, a metal structure is grown from an internal surface toward an external surface of the base material using an electrolytic solution in which a phosphorus ion has been added to a nickel ion, while a concentration of the phosphorus ion in the electrolytic solution is gradually increased in that process. As a result, hardness in the external surface of the base material in the fixing belt is lower than that in the internal surface
However, the durability of the fixing belt cannot be sufficiently enhanced depending on how to add phosphorus to the base material in the fixing belt, and consequently an exchange lifetime of the fixing belt is likely shortened.